People who consume plenty of vitamin B12 have a significantly lower risk of developing Alzheimer’s Disease, researchers from the Karolinska Institutet, Stockholm, Sweden, revealed in an article published in the peer-reviewed journal Neurology. Good sources of vitamin B12 include, poultry, fish, meat products, eggs and dairy products. Many vegan foods today are supplemented with vitamin B12, which is vital for the synthesis of red blood cells, maintenance of the nervous system, and the growth and development of children. People with a vitamin B12 deficiency are much more likely to develop anemia.

The researchers write that their study provides more compelling evidence regarding the vitamin’s role in preventing memory loss.

They add that their study reveals the need for more research into vitamin B12’s role as a marker for identifying individuals at higher risk of developing Alzheimer’s Disease.

Doctoral Student Babak Hooshmand, at the Department of Neurobiology, Care Sciences and Society, the Karolinska Institutet, said:

Low levels of vitamin B12 are surprisingly common in the elderly. However, the few studies that have investigated the usefulness of vitamin B12 supplements to reduce the risk of memory loss have had mixed results.

In this study, blood samples were taken from 271 Finnish individuals from the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study, they were aged between 65 and 79 years – none of them had symptoms of dementia when the study began. Over a period of seven years of follow-up 17 of them developed Alzheimer’s Disease.

Blood levels of homocysteine were measured. Homocysteine is an amino acid, its chemical formula is HSCH2CH2CH(NH2)CO2H, and is a homologue (an organic compound with a similar general formula) of the amino acid cysteine. High levels of homocysteine have been associated with an increased incidence of cardiovascular disease – lowering its levels might not improve outcomes. High blood homocysteine levels are also linked to negative effects on the brain, such as stroke. However, elevated levels of vitamin B12 can help lower homocysteine levels.

The scientists found that for every decrease of 1 micromole per liter of homocysteine in the blood, Alzheimer’s Disease (AD) risk went up by 16%. On the other hand, for every increase of 1 micromole per liter of the active part of vitamin B12 (holotranscobalamin), the risk of AD dropped by 2%. These figures remained the same, even after taking into account the patient’s age, education, smoking habits, blood pressure, body mass and gender. The addition of folate (folic acid) did not change any of the results.

The authors concluded:

This study suggests that both tHcy* and holoTC** may be involved in the development of AD. The tHcy-AD link may be partly explained by serum holoTC. The role of holoTC in AD should be further investigated.

* tHcy = homocysteine.
** holoTC = holotranscobalamin (the active part of vitamin B12)

“Homocysteine and holotranscobalamin and the risk of Alzheimer disease – A longitudinal study”
B. Hooshmand, MD, MSc, A. Solomon, MD, PhD, I. Kåreholt, PhD, J. Leiviskä, MSc, M. Rusanen, MD, S. Ahtiluoto, MD, B. Winblad, MD, PhD, T. Laatikainen, MD, PhD, H. Soininen, MD, PhD and M. Kivipelto, MD, PhD
NEUROLOGY 2010;75:1408-1414

Written by Christian Nordqvist